Immunologic status in physiological pregnancy

The levels of T gamma- and T mu-lymphocytes, functional activity of ConA-induced T-suppressors and the concentrations of SP1 and SP3 were determined in 164 normal pregnant women during 8-40 weeks of gestation. It is found that formation of the suppressor dominant is necessary for the immunological maintenance during 8-32 weeks of gestation. This dominant is intended to block superfluous maternal immune response to fetal alloantigens. The formation of such a dominant is evoked by high functional activity of ConA-induced T-suppressors and high levels of T gamma-lymphocytes with immunodeficiency of T mu-cells. Results of correlation analysis have shown a relationship between functional activity of T-suppressors and accumulation of two specific pregnancy proteins. It permits determining physiological role of SP1 and SP3 as natural endogenous immunoregulators of T-suppressors.     

Surfactant protein of molecular weight 28,000-36,000 in cultured human fetal lung: cellular localization and effect of dexamethasone

We have examined the effect of explant culture and hormones on the major surfactant associated protein of Mr 28,000-36,000 (SP 28-36) in human fetal lung. Explants of 16- to 23-week gestation lung were maintained for up to 5 days in culture. Polyclonal antibodies raised to SP 28-36 purified from alveolar proteinosis lung lavage were used in immunofluorescence experiments (n = 11). There was no specific fluorescence seen in frozen sections of preculture tissue. In explants cultured without serum or hormones, fluorescence was seen in most epithelial cells lining potential airspaces. In cultures treated with 10 nM dexamethasone and 2 nM T3 much brighter fluorescence was seen in virtually all epithelial cells. Immunofluorescence studies on cell monolayers prepared from explants confirmed that SP 28-36 is found in the cytoplasm of type II cells but not in fibroblasts. The pattern of fluorescence was consistent with the presence of SP 28-36 on rough endoplasmic reticulum. SP 28-36 mRNA was measured in isolated cell populations using a 32P-labeled cDNA probe. mRNA levels were manyfold higher in type II cell preparations (purity 78-92%) than in fibroblasts (purity 81-97%). A competitive enzyme linked assay was developed to quantify SP 28-36. The SP 28-36 content of five lungs before culture (17-23 weeks) was less than 0.02 microgram/mg DNA. During explant culture without hormones the SP 28-36 content increased exponentially. Exposure to dexamethasone accelerated the increase in SP 28-36 content. T3, alone or in the presence of dexamethasone, did not influence SP 28-36 content. We conclude that SP 28-36 content is very low in human fetal lung before 24 weeks gestation. Explant culture and treatment with dexamethasone synchronize development of type II cells from epithelial precursors, and induce synthesis of SP 28-36 in type II cells. These findings provide evidence of concomitant regulation by glucocorticoids of the phospholipid synthetic enzymes and the major protein of pulmonary surfactant.     

Activity and expression of different members of the caspase family in the rat corpus luteum during pregnancy and postpartum

Studies were designed to examine the expression and activity of four caspases that contribute to the initial (caspases-2, -8, and -9) and final (caspase-3) events in apoptosis in the rat corpus luteum (CL) during pregnancy (days 7, 17, 19, and 21 of gestation), postpartum (days 1 and 4), and after injection (0, 8, 16, 24, and 36 h) of the physiological luteolysin PGF2alpha. In addition, the temporal relationship of caspase expression/activity relative to steroid production and luteal regression was evaluated. During pregnancy, the activity of all four caspases was significantly greater on day 19, before a decline in CL progesterone (P) and CYP11A1 levels at day 21 of gestation. The levels of the caspase-3 active fragment (p17, measured by Western blot) also increased at days 19 and 21 of pregnancy. Immunohistochemical analyses detected specific staining for the caspases in luteal cells (large and small) as well as in endothelial cells. However, the percentage of apoptotic cells did not increase in the CL until postpartum. Following PGF2alpha injection, there was a significant decrease in CL P by 24 h, although the activity of all four caspases did not increase until 36 h posttreatment. The active p17 fragment of caspase-3 also significantly increased at 36 h post-PGF2alpha. These results suggest that an increase in the activity of caspases-2, -8, -9, and -3 is associated with the early events of natural luteolysis at the end of pregnancy. Also, the exogenous administration of the luteolysin PGF2alpha may regulate members of the caspase family.     

Risk of premature birth in multifetal pregnancy.

The risk of preterm delivery (< 37 weeks of gestation) is approximately nine times higher in women with multifetal pregnancies than in women with singleton pregnancies. However, it is possible that the risk will vary according to gestational week. To assess the risk of premature birth within 1 week by gestational age among multifetal pregnancies and compare the estimated risk with that of singleton pregnancies, we analyzed 6,036,475 infants born in singleton pregnancies and 90,887 infants born in multifetal pregnancies in Japan (> or =22 weeks) over the 5-year period 1989-1993. An estimate of the risk of birth within 1 week at gestational week n was obtained by dividing the number of infants delivered at gestational week n by the number of infants delivered at or beyond gestational week n. The risk at 22 weeks was 0.9 per 1000 fetuses for singleton pregnancies and 5.0 per 1000 for multifetal pregnancies. The risk remained relatively stable until 27 weeks of gestation, then sharply increased toward 36 weeks of gestation in both singleton and multifetal pregnancies. The odds ratio for birth within 1 week for fetuses of multifetal pregnancies compared with fetuses of singleton pregnancies was 5.9 (95% CI, 5.4-6.5) at 22 weeks of gestation, increasing gradually with increasing gestational age until 33 weeks of gestation (13.7; 95% CI, 13.1-14.2) but declining thereafter to 8.8 (95% CI, 8.6-8.9) at 36 weeks of gestation. Results of data analysis for each year of the 5-year period did not differ substantially.     

EEG characteristics of bioelectrical activity of the brain in women with normal and complicated pregnancy

Spectrum and coherent EEG analysis has been made at 109 pregnant women during 35-36 weeks of gestation. It has been shown, that functional interhemispherical asymmetry of the brain is the sensible parameter of normal and complicated gestation. It has been found out that as for normal pregnancy prevailing activation in central and temple areas of the brain contralateral to the side of placenta placement in uterus is characteristic. The development of gestation complications accompanied by the inversion of interhemispherical asymmetry of EEG activation. It was pointed out that correlative relations of bioelectrical activity of the brain in women with normal gestation are the indicator of dominating of nervous centers of left hemisphere in the integrational process.     

Plasma lipids and apolipoproteins A and B in human pregnancy

A cross sectional study was carried out in 200 normal pregnant women between 8-40th weeks of gestation, 25 women during delivery and 25 women 6 weeks after delivery. Plasma and lipoprotein lipids were measured using standard procedures. Apolipoprotein A (Apo A) and Apolipoprotein B (Apo B), were measured by electroimmunoassay. Plasma levels of Apo A were elevated in pregnant women but the elevations were not significant until 17-20 weeks of gestation. Apo A during pregnancy was significantly correlated (p less than 0.001) with high density lipoprotein cholesterol (HDL-C). The level of Apo B increased progressively during pregnancy and it was significantly correlated (p less than 0.001) with total cholesterol (TC), plasma triglycerides (TG) and phospholipids (PL). Apo A and Apo B levels returned to non pregnant values within the puerperium, whereas TC, TG and PL remained significantly elevated above controls (p less than 0.01) 6 weeks post partum.     

Low polarity ligands of sex hormone-binding globulin in pregnancy. Part I--Characterization

Certain previously unidentified substances of low polarity binding to the sex hormone binding globulin (SHBG) in pregnancy were investigated. This material consisted of four major peaks (designated 1a, 1b, 2 and 3) as defined in maternal serum on Sephadex LH-20 chromatography. They were characterized with respect to changes in their concentration at various gestational ages and at premature and term labour in maternal serum, cord serum, placenta and maternal urine. Levels were much higher in placenta than in serum, suggesting that all four peaks were of placental origin. In the serum of mothers not in labour, while there was a significant increase in the mean serum concentration of peak (1a + 1b) and peak 3 for 12-24 weeks to 30-38 weeks gestation, there was no significant difference in the mean level of peak 2. However, there was a significant decrease in the serum levels of peak 2, but not peaks (1a + 1b) and 3, from 30-38 weeks gestation to 39-41 weeks gestation (P less than or equal to 0.05). In the serum of mothers in premature labour (30-38 weeks gestation), the levels of peak 2 but not those of peak (1a + 1b) and 3, were decreased (P less than or equal to 0.01) compared to those not in labour. These findings are consistent with the identification of peak 1a as 5 alpha-dihydroprogesterone, peak 1b as progesterone and peak 3 as 2-methoxyestrone as described in part 2. The decrease in the levels of peak 2 (for which the identification remains unconfirmed) in association with premature and impending term spontaneous labour suggest that it may be involved in the maintenance of pregnancy.     

Activity of arylamidases in serum during normal pregnancy.

Activity of arylamidases toward 6 beta-naphthylamides of L-amino acids was studied in the blood serum from 110 healthy women between the 6th and 36th weeks of pregnancy. A regular increase in the enzymatic activity was demonstrated toward all substrates under examination, particularly in the presence of alanyl-, leucyl- and lysyl-beta-naphthylamides, most pronounced in the last trimester of gestation. A correlation between oxytocinase and arylamidases activity was demonstrated, suggesting a possibility of using the enzymatic measurement as a diagnostic test in the normal course of pregnancy.     

Deoxycytidylate deaminase in pregnancy.

Deoxycytidylate (DCMP) deaminase was assayed at various times during and after normal and abnormal pregnancies. The level in amniotic fluid was assessed at induction and at caesarean section, and cord blood levels were estimated after normal delivery and at caesarean section. A rise occurred during labour and after hysterectomy and caesarean section--returning to normal after 2-3, and 12 days respectively. Levels above 4.8 X 10-minus 4 ml-minus 1 were found in cases of preeclamptic toxaemia and early intrauterine death and in twin pregnancies over 36 weeks'' gestation. It is suggested that because of its low incidence of false-negative and false-positive results this test is far superior to other enzyme tests in pregnancy, and a further trial is in progress to assess its role.     

Residual B-cell function and glycaemic control in diabetic pregnancy

Serum C-peptide immunoreactivity (CPR), mean blood glucose and blood glycosylated haemoglobin Hb A1c were measured in 23 insulin-dependent diabetic women at 11-12, 23-24, 33-34 and 37-38 gestational weeks in order to elucidate changes in residual B-cell function during pregnancy and their influence on the glycaemic control. CPR values generally increased at the 23-33 gestational weeks, with a significant difference between the mean of the peak values and the mean of the values at the first admission. When the subjects were divided into two groups on the basis of the residual B-cell function at the first admission, the glycaemic control during pregnancy was significantly better in those with higher residual B-cell activity. The overall prevalence of marked residual B-cell activity was higher than previously reported in non-pregnant insulin-dependent diabetic subjects. The results indicate clinically important enhancement in residual B-cell function during pregnancy. The mechanism of this improvement is poorly known although the more strict management of diabetes during gestation may be an important factor.     

Endocrine changes during pregnancy, parturition and post-partum in guanacos (Lama guanicoe)

Plasma concentrations of progesterone (P4), estradiol-17β (E2), estrone (E1) and estrone sulfate (E1S) were measured during gestation in eight guanacos kept in captivity. Gestational length was 346.1 ± 9.8 days. P4 plasma concentrations increased after ovulation and remained elevated until parturition. However, during the last 4 weeks of gestation, a gradual decrease from 4.17 × 1.17^±1 nmol/L to 2.02 × 1.95^±1 nmol/L on day 5 before parturition was observed, followed by a more abrupt final decline to baseline concentrations which were reached on the day after parturition. Mean E2 plasma concentrations started to increase during the eighth month of gestation, and were significantly elevated up to maximum concentrations of 484.7 × 1.21^±1 pmol/L during the last 2 months of pregnancy. Concentrations returned to baseline during the last 2 days of gestation. An increase of E1S concentrations (p < 0.01) was observed in the eleventh month of gestation. Mean E1S concentrations remained rather constant during the last 3 weeks of gestation between 4 to 8 nmol/L until parturition, when a steep precipitous decline was observed. E1 concentrations were slightly elevated during the last 4 weeks of gestation, however, maximum concentrations did not exceed 1.5 nmol/L. The results show distinct species specific features of gestational steroid hormone profiles in the guanaco in comparison to domestic South American camelids, such as a more pronounced gradual prepartal decrease of P4 concentrations prior to the final decline to baseline, and clearly lesser E1S concentrations during the last 4 weeks of gestation, which lack a continuous prepartal increase.     

Absorption of non-haem iron from food during normal pregnancy.

OBJECTIVE--To determine whether the increased iron demands of pregnancy could be met by increased absorption from dietary sources. DESIGN AND SETTING--Longitudinal prospective study in the research unit of a maternity hospital. SUBJECTS--12 normal pregnant women. INTERVENTIONS--At 12, 24, and 36 weeks'' gestation (within one week) and 16-24 weeks after delivery women ate a breakfast of meat, bread, and orange juice (3.2 mg iron), extrinsically labelled with the stable isotope iron-54 (2.8 mg); the stable isotope iron-57 (200 micrograms) was given intravenously. MAIN OUTCOME MEASURES--Serum samples were taken for 10 hours after administration of the isotopes; ratios of the isotopes were measured by inductively coupled plasma mass spectrometry, and the absorption of oral iron was calculated. RESULTS--The geometric mean (95% confidence interval) absorption of iron at 12, 24, and 36 weeks'' gestation was 7% (5% to 11%), 36% (28% to 47%), and 66% (57% to 76%) respectively. At 16-24 weeks after delivery the absorption was 11% (6% to 21%). The mean increase in absorption at 36 weeks (compared with that at 12 weeks) was 9.1 times (6.0 to 13.7). One pregnant woman developed iron deficiency anaemia but was otherwise indistinguishable from the others. CONCLUSIONS--An increase in the absorption of iron from food is a physiological consequence of normal pregnancy, not the result of developing anaemia during pregnancy, and such an increase is large enough to meet the increased requirements of pregnancy provided that the dietary intake is adequate.     

Increase in placental 15-hydroxy-prostaglandin dehydrogenase in the first half of human pregnancy

NAD-dependent 15-hydroxy-prostaglandin dehydrogenase (PGDH) activity was measured in homogenates of 25 human placentae obtained between 7 and 17 weeks of gestation. PGDH activity, expressed in nanomoles PGF2 alpha metabolized per min, ranged from 0.2 to 5.4 nmoles per mg placental protein and from 1.5 to 80 nmoles per g wet weight. PGDH activity per mg protein and per g weight increased significantly in function of gestational age (p less than 0.001). Between 7-8 weeks' gestation and 15-16 weeks mean values increased tenfold from 0.4 to 3.0 nmoles per mg protein and from 2.7 to 36.6 nmoles per g wet weight. Per unit of weight these early placentae contained less PGDH activity than term controls, but this related mainly to their high water content. Per mg placental protein PGDH activities already equalled values found at term before the end of the first trimester. The data indicate that the development of terminal villi and the migration of trophoblast into the maternal spiral arteries is associated with a substantial increase in the placental capacity for prostaglandin metabolism.     

Increase in placental 15-hydroxy-prostaglandin dehydrogenase in the first half of human pregnancy

NAD-dependent 15-hydroxy-prostaglandin dehydrogenase (PGDH) activity was measured in homogenates of 25 human placentae obtained between 7 and 17 weeks of gestation. PGDH activity, expressed in nanomoles PGF_2α metabolized per min, ranged from 0.2 to 5.4 nmoles per mg placental protein and from 1.5 to 80 nmoles per g wet weight. PGDH activity per mg protein and per g weight increased significantly in function of gestational age (p<0.001). Between 7–8 weeks' gestation and 15–16 weeks mean values increased tenfold from 0.4 to 3.0 nmoles per mg protein and from 2.7 to 36.6 nmoles per g wet weight. Per unit of weight these early placentae contained less PGDH activity than term controls, but this related mainly to their high water content. Per mg placental protein PGDH activities already equalled values found at term before the end of the first trimester. The data indicate that the development of terminal villi and the migration of trophoblast into the maternal spiral arteries is associated with a substantial increase in the placental capacity for prostaglandin metabolism.     

Purification and characterization of early pregnancy factor from human pregnancy sera

Early pregnancy factor (EPF) is a pregnancy-associated protein detected in the maternal serum by using the rosette inhibition assay and by evaluating the suppression of adoptive transfer of contact sensitivity. Because of its inhibitory effect on the functional reactivity of immunocompetent cells, EPF is thought to be involved in immunoregulation of the maternal immune system during early pregnancy. EPF was purified six million-fold from the serum of pregnant women between 5 and 12 weeks of gestation. The specific activity of purified EPF was approximately 8 x 10(8) units/mg. The purification scheme involved sequential DEAE-cellulose chromatography, S-Sepharose chromatography, concanavalin A-Sepharose chromatography, heparin-Sepharose chromatography, Mono S fast protein liquid chromatography, and preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The purified protein has an apparent molecular weight of 21,500 as analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and 28,000 by gel permeation high pressure liquid chromatography. The isoelectric point of purified EPF moiety is 6.5. The biological activity was susceptible to the proteolytic enzyme trypsin, acidic pH conditions, organic solvents, and sodium dodecyl sulfate, but stable to heat treatment at 56 degrees C for 30 min and the reducing agent dithiothreitol. The biological and physicochemical properties of EPF appear to be distinct from other pregnancy-associated and immunoregulatory proteins.     

Intermittent screening and treatment versus intermittent preventive treatment of malaria in pregnancy: a randomised controlled non-inferiority trial

Background

The effectiveness of intermittent preventive treatment of malaria in pregnancy (IPTp) may be compromised by the spread of resistance to sulphadoxine/pyrimethamine (SP) across Africa. But little informtion exists on alternative drugs for IPTp or alternative strategies for the prevention of malaria in pregnancy. Therefore, we have investigated whether screening with a rapid diagnostic test and treatment of those who are positive (IST) at routine antenatal clinic attendances is as effective and as safe as SP-IPTp in pregnant women.

Methods and Findings

During antenatal clinic sessions in six health facilities in Ghana held between March 2007 and September 2007, 3333 pregnant women who satisfied inclusion criteria were randomised into three intervention arms (1) standard SP-IPTp, (2) IST and treatment with SP or (3) IST and treatment with amodiaquine+artesunate (AQ+AS). All women received a long-lasting insecticide treated net. Study women had a maximum of three scheduled follow-up visits following enrolment. Haemoglobin concentration and peripheral parasitaemia were assessed between 36 and 40 weeks of gestation. Birth weight was measured at delivery or within 72 hours for babies delivered at home. Parasite prevalence at enrolment in primigravidae and in multigravidae was 29.6% and 10.2% respectively. At 36–40 weeks of gestation the prevalence of asymptomatic parasitaemia was 12.1% in study women overall and was very similar in all treatment groups. The risk of third trimester severe anaemia or low birth weight did not differ significantly between the three treatment groups regardless of gravidity. IST with AQ+AS or SP was not inferior to SP-IPTp in reducing the risk of low birth weight (RD = -1.17[95%CI; -4.39-1.02] for IST-SP vs. SP-IPTp and RD = 0.78[95%CI; -2.11-3.68] for IST-AQAS vs. SP-IPTp); third trimester severe anaemia (RD = 0.29[95%CI; -0.69-1.30] for IST-SP vs. SP-IPTp and RD = -0.36[95%CI;-1.12-0.44] for IST-AQAS vs. SP-IPTp).

Conclusion

The results of this study suggest that in an area of moderately high malaria transmission, IST with SP or AS+AQ may be a safe and effective strategy for the control of malaria in pregnancy. However, it is important that these encouraging findings are confirmed in other geographical areas and that the impact of IST on placental malaria is investigated.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00432367","term_id":"NCT00432367"}}NCT00432367 [{"type":"clinical-trial","attrs":{"text":"NCT00432367","term_id":"NCT00432367"}}NCT00432367]     

Ultrasonography in early pregnancy diagnosis and measurements of fetal size in reindeer (Rangifer tarandus tarandus)

Transrectal or transabdominal examinations of 13 pluriparous reindeer (Rangifer tarandus tarandus) by ultrasonography from the start of mating until week 20 of gestation were conducted to find out when pregnancy could first be detected and to describe fetal development in early pregnancy. The examinations (n=35 per animal) were performed with a 5 MHz linear transducer from 7th October until 1st January and with a 3 MHz sector transducer from that time until 24th February. Time of pregnancy diagnosis by ultrasonography, the first fetal heartbeat and measurements of crown-rump length, chest width and chest depth were recorded during the examinations. Pregnancy was diagnosed by transrectal ultrasonography between the weeks 3 and 7 of gestation. The accuracy of the pregnancy diagnosis, defined as the proportion of females correctly detected to be pregnant, was 15% at week 3, 46% at week 4, 77% at week 5, and 92% at week 6 of gestation. Fetal heartbeat was first detected between the weeks 5 and 8 of gestation. The first measurements of crown-rump length were made on week 3 of gestation, of chest width on week 4 and of chest depth on week 5 of gestation. Chest width and depth were detectable until the end of the study at week 20 of gestation. Transrectal ultrasonography is an efficient tool in early pregnancy diagnosis of reindeer. The fetal growth curves obtained by ultrasonography resembled those obtained in previous morphological studies.     

Synthesis of sperm-specific basic nuclear proteins (SPs) in cultured spermatids from Xenopus laevis

The accumulation and synthesis of sperm-specific basic nuclear proteins (SPs) in Xenopus spermatids in vitro were studied by acid-urea-Triton polyacrylamide gel electrophoresis and fluorography. In synchronous cultures of round spermatids, the amount of SP2 and SP3-5 accumulated almost linearly with time, while that of SP1 remained almost constant. Fluorography showed that round spermatids incorporated [14C]arginine mostly into SP1 and SP3-5, very little into SP2, and none into histones. When [14C]arginine was incorporated into cells for 24 h on Days 0, 3, and 6, followed by immediate extraction of basic nuclear proteins, the SP1 band was detected faintly on Day 0 and the intensity increased to the maximum level by Day 3 and remained constant on Day 6; the SP3-5 bands were first detected on Day 3 and their intensity increased by Day 6. Thus, SP1 and SP3-5 were synthesized differentially during the culture period. When [14C]arginine or [14C]lysine was incorporated into round spermatids on Days 0, 3, and 6 for 15 h and chased for 3-12 days, the intensity of the SP2 band increased significantly, while the intensity of the SP1 band decreased concomitantly. This result indicates that SP2 was processed from a precursor protein which is probably SP1.     

Glycosphingolipid Glycosyltransferases in Human Fetal Brain

The developmental pattern of gangliosides in human fetal brain should reflect the activities of the respective glycosyltransferases. LA2-synthase activity, along with that of GM3-, GD3-, GM2-, and GM1-synthases, was determined in human fetal brain at 10-22 weeks of gestation. LA2-synthase is the pivotal enzyme in lacto series ganglioside formation. LA2-synthase activity decreased during the study period, mirroring a similar temporal decline in levels of the lacto series gangliosides, particularly 3'-isoLM1. The developmental profiles of the ganglio series glycosyltransferase activities demonstrate distinct changes that correspond to the ganglioside pattern between fetal weeks 10 and 22. In particular, the marked increase in GM2-synthase activity at 20 and 22 weeks of gestation and the decline in GD3-synthase activity after 15 weeks could explain the prominent expression of the a series gangliosides in this period of rapid neuronal outgrowth. However, a similar decline (two- to 2.5-fold) in GM3-synthase activity suggests a more likely conclusion, namely, that the two sialyltransferase activities are derived mainly from astroglial cells, which show a marked proliferation during the 10-15th fetal weeks. The data do not negate the hypothesis that GM3- and GD3-synthase are the critical enzymes in the regulation of ganglioside biosynthesis but do indicate a need to reevaluate the significance of GM2-synthase in expression of the a series gangliosides.     

The major lung surfactant protein, SP 28-36, is a calcium-dependent, carbohydrate-binding protein

SP 28-36, a major protein of pulmonary surfactant, has striking amino acid sequence homology with soluble mannose-binding proteins isolated from rat liver and contains residues common to the carbohydrate-binding domains of other mammalian lectins. We have used carbohydrate-affinity chromatography to investigate carbohydrate-binding properties of SP 28-36 isolated from canine and human (alveolar proteinosis patients) lung lavage. SP 28-36 binds to immobilized D-mannose, L-fucose, D-galactose, and D-glucose. The protein binds only weakly to N-acetyl-D-galactosamine and N acetyl-D-glucosamine. Binding is Ca2+-dependent. The threshold Ca2+ concentration is 0.6 mM and maximal binding occurs with 1 mM Ca2+. Bound protein is quantitatively recovered by elution with 2 mM EDTA. Ba2+, Sr2+, and Mn2+, but not Mg2+, can substitute for Ca2+. Unlike some other mammalian lectins, SP 28-36 binds to carbohydrate at pH 5.0. Recombinant human SP 28-36 isolated from the media of Chinese hamster ovary cells, transfected with a DNA construct encoding SP 28-36, has similar carbohydrate-binding activity to the native proteins. Mannose affinity chromatography of the culture medium of Chinese hamster ovary cells results in an efficient purification of the secreted recombinant human SP 28-36.